It is known to provide a motor vehicle having a four wheel drive mode of operation in which motive power is supplied to each of two pairs of wheels of the vehicle. Motive power is supplied to the wheels by means of a driveline.
Some known vehicles are arranged such that motive power is permanently supplied to both pairs of wheels. Some other vehicles are arranged such that motive power is selectively supplied to either only one pair or to both pairs of wheels. A driver operable selector may be provided to allow the driver to select two wheel or four wheel operation. Some driveline systems require the vehicle to be stationary when transitioning between two and four wheel drive modes. Such systems may be referred to as static disconnect/reconnect systems.
GB2407804 discloses a dynamic driveline reconnect arrangement in which reconnection of two of the wheels to the driveline following disconnection of the wheels from the driveline may be undertaken when the vehicle is moving. The system disclosed in GB2407804 employs clutch arrangements to enable dynamic driveline reconnection.
In some known dynamic driveline reconnect systems the vehicle is operable automatically to connect the driveline such that both pairs of wheels are driven by the engine when a prescribed condition is met so that the vehicle operates in a four wheel drive mode. The system automatically disconnects the driveline from one of the pairs to enable two wheel drive operation when the prescribed condition is not met.
It is an aim of embodiments of the present invention to provide an improved dynamic driveline system.